1. Field of the Invention
The invention relates to a method for the batch production of steel in an oxygen steel converter, in which a charge comprising solid scrap is loaded into the converter, the scrap is melted and the charge is refined in the converter by means of an oxygen blowing lance, which is inserted into the converter through its mouth. Finally the steel is tapped out of the converter.
2. Description of the Prior Art
The above paragraph describes the classical oxygen steel process, which is used on a large scale worldwide. In this process, the percentage by weight of the scrap in the charge is confined within narrow limits, and lies in the range from 20% to 30% maximum. This known process forms the basis for the present invention.
For a long time there has been a need for more freedom in the use of scrap and pig iron raw materials in the oxygen steel process, particularly with a view to a higher scrap content, for example in the event of a pig iron shortage or low scrap prices.
From Stahl und Eisen 101 (1981), page 639, there is known the KS process, in which a higher scrap input is used in an OBM converter. In this very special type of converter, fuel and oxygen are fed in through the bottom of the converter in order to cause the scrap to melt. However, most oxygen steel converters are not equipped for the supply of fuel and oxygen through the bottom of the converter in the quantities needed for scrap melting. With an OBM converter, there can also be problems in supplying fuel and oxygen in sufficient quantities through the trunnions of the converter. However, if fuel and oxygen are not fed via the trunnions, tilting of the converter is impeded.
The KVA process is known from EP-A-0240485, in which scrap is melted in a shaft furnace, then tapped off and finally refined in a converter. This process requires high investment for the shaft furnace and special provisions for scrap supply and for holding the molten scrap at temperature. Likewise, DE-B-1800610 describes melting of scrap in a separate furnace vessel, using a burner lance whose lower end is at the bottom of the vessel.
DE-A-1433452 and DE-A-2759129 illustrate processes in which a solid charge in a converter is heated from on top.